The LASIK Procedure: A Complete Guide

LASIK, or "laser-assisted in situ keratomileusis," is the most commonly performed laser eye surgery to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.

Like other types of refractive surgery, the LASIK procedure reshapes the cornea to enable light entering the eye to be properly focused onto the retina for clearer vision.

In most cases, laser eye surgery is pain-free and completed within 15 minutes for both eyes. The results  improved vision without eyeglasses or contact lenses  can usually be seen in as little as 24 hours.

If you're not a good LASIK candidate, a number of other vision correction surgeries are available, such as PRK and LASEK laser eye surgery and phakic IOL surgery. Your eye doctor will determine if one of these procedures is suitable for your condition and, if so, which technique is best.

How Is LASIK Surgery Performed?

First, your eye surgeon uses either a mechanical surgical tool called a microkeratome or a femtosecond laser to create a thin, circular "flap" in the cornea.

Want a visual? View our LASIK slide show!

The surgeon then folds back the hinged flap to access the underlying cornea (called the stroma) and removes some corneal tissue using an excimer laser.

This highly specialized laser uses a cool ultraviolet light beam to remove ("ablate") microscopic amounts of tissue from the cornea to reshape it so it more accurately focuses light on the retina for improved vision.

For nearsighted people, the goal is to flatten the cornea; with farsighted people, a steeper cornea is desired.

Excimer lasers also can correct astigmatism by smoothing an irregular cornea into a more normal shape. It is a misconception that LASIK cannot treat astigmatism.

After the laser reshapes the cornea, the flap is then laid back in place, covering the area where the corneal tissue was removed. Then the cornea is allowed to heal naturally.

Laser eye surgery requires only topical anesthetic drops, and no bandages or stitches are required.

Before LASIK Surgery

Your eye doctor will perform a thorough eye exam to ensure your eyes are healthy enough for the procedure. He or she will evaluate: the shape and thickness of your cornea; pupil size; refractive errors (myopia, hyperopia and astigmatism); as well as any other eye conditions.

The moistness of your eyes will also be evaluated, and a precautionary treatment may be recommended to reduce your risk of developing dry eyes after LASIK.

Usually, an automated instrument called a corneal topographer is used to measure the curvature of the front surface of your eye and create a "map" of your cornea.

With wavefront technology associated with custom LASIK, you also are likely to undergo a wavefront analysis that sends light waves through the eye to provide an even more precise map of aberrations affecting your vision.

Your eye doctor will also note your general health history and any medications you are taking to determine if you are a suitable candidate for LASIK.

You should stop wearing contact lenses for a period of time advised by your doctor (typically around two weeks) before your eye exam and before the LASIK procedure, as contacts can alter the natural shape of your cornea.

What To Expect During LASIK

Before your surgery begins, numbing eye drops are applied to your eye to prevent any discomfort during the procedure. Your doctor may also give you some medication to help you relax.

Your eye will be positioned under the laser, and an instrument called a lid speculum is used to keep your eyelids open.

The surgeon uses an ink marker to mark the cornea before creating the flap. A suction ring is applied to the front of your eye to prevent eye movements or loss of contact that could affect flap quality.

After the corneal flap is created, the surgeon then uses a computer to adjust the excimer laser for your particular prescription.

You will be asked to look at a target light for a short time while he or she watches your eye through a microscope as the laser sends pulses of light to your cornea.

Immediately After LASIK Surgery

Upon completion of your LASIK surgery, your surgeon will have you rest for a bit. You may feel a temporary burning or itching sensation immediately following the procedure. After a brief post-operative exam, someone can drive you home. (You cannot drive after LASIK until your eye doctor sees you the following day and confirms your uncorrected vision meets the legal standard for driving.)

LASIK Surgery Checklist

Choose an experienced LASIK surgeon. How many LASIK procedures has your doctor performed? Does he or she use state-of-the-art equipment and technology?

Be honest with your doctor. Have you alerted your eye doctor about any health issues you have or medications you are taking?

Generally, you will return to see your eye doctor or your LASIK surgeon the day after surgery.

At this initial check-up, he or she will test your vision to make sure you are legal to drive without glasses or contact lenses. In most states, this requires uncorrected visual acuity of 20/40 or better.

As with any other surgery, always follow your doctor's instructions and take any medication prescribed. Also, avoid rubbing your eyes, as there's a small chance this could dislodge the flap until it heals and adheres more securely to the underlying cornea.

Long-Term Results

Laser eye surgery offers numerous benefits and can dramatically improve your quality of life. Most people achieve 20/20 vision or better after the surgery, but LASIK results do vary. Some people may achieve only 20/40 vision or less.

You may still need to wear glasses or contact lenses following laser vision correction, though your prescription level typically will be much lower than before.

If you have mild residual refractive error after LASIK and you want sharper vision for certain activities like driving at night, prescription lenses with anti-reflective coating often can be helpful. Also, if you are sensitive to sunlight after LASIK, ask your eye care professional about eyeglasses with photochromic lenses.

While the procedure has an excellent safety profile, LASIK complications can occur and may include infection or night glare (starbursts or halos that are most noticeable when you're viewing lights at night, such as while you're driving).

A small percentage of people will need a LASIK enhancement, or "touch up" procedure, a few months after the primary LASIK surgery to achieve acceptable visual acuity.

You also may still need reading glasses once you reach your 40s, due to a normal age-related loss of near vision called presbyopia.

While LASIK surgery has a high success rate, it is important that you discuss all facets of the procedure with your surgeon prior to consenting to the surgery.

Latest LASIK Outcomes Are Better Than Ever, Researchers Find

September 2016  Outcomes of modern LASIK surgery, as measured by visual acuity, refractive results and patient satisfaction, are better than ever, according to a meta-analysis of recent studies of the vision correction procedure.

A team of researchers from refractive surgery centers across the United States and in Germany analyzed the results of 97 LASIK studies published between 2008 and 2015. The outcomes of nearly 68,000 eyes that had undergone the procedure were evaluated.

98.6 percent of eyes were within +/- 1.0 diopter (D) of the target refractive outcome.

90.9 percent of eyes were within +/- 0.5 D of the target refractive outcome.

98.8 percent of patients reported being satisfied with their LASIK results.

Outcomes of these recently published studies were better than those reported in summaries of the safety and effectiveness of earlier laser refractive surgery systems approved by the U.S. Food and Drug Administration (FDA), according to the study authors. The results support the safety, efficacy and patient satisfaction of the procedure, they concluded.

A full report appeared in the August 2016 issue of Journal of Cataract & Refractive Surgery.  G.H.

About the Reviewer: Brian Boxer Wachler, MD, is an ophthalmologist and refractive surgeon at the Boxer Wachler Vision Institute in Beverly Hills, Calif. He has pioneered treatments for keratoconus, participated in many FDA clinical trials for new refractive surgery technologies and written several books. He is a member of All About Vision's editorial advisory board.